1. General Seminars

Special Relativity from Quantum Theory: Simulation of Quantum Fields by a Quantum Computer as a new type of QFT

by Dr Giacomo Mauro D'Ariano (Dip. Fisica "A. Volta" Univ. Pavia)

Aula A1 (Laboratori Nazionali di Frascati)

Aula A1

Laboratori Nazionali di Frascati

Are Quantum Mechanics and Special Relativity unrelated theories? Is Quantum Field Theory (QFT) an additional theoretical layer over them? Where the quantization rules and the Plank constant come from? All these questions can find answer in the computational paradigm: "the universe is a huge quantum computer". If one takes the computational-universe paradigm seriously as a new theoretical framework, a new kind of quantum field theory unfolds: the "Quantum-Computational Field Theory" (QCFT). In QCFT Special Relativity comes out from the fabric of the computational network, which also naturally embeds gauge-invariance, and even the quantization rule and the Planck constant, which thus resort to being properties of the underlying causal tapestry of space-time. In this way Quantum Mechanics remains the only theory needed to describe the computational-universe. I will show how Special Relativity can be derived from a causal network that is topologically homogeneous. I will restrict the analysis to a network that can be embedded in two dimensional plane. I will then show that the requirement that the speed of light coincides with the causal speed implies that the quantum field is an infinite quantum computer with finite (not infinitesimal) gates. For a massless field gates are just swaps. Inertial mass is just interaction between left and right propagating qubits (fields) producing a Zitterbewegung slowing-down from causal speed. Unitarity then implies a tradeoff between the coupling (Compton wavelength) and the coarse-grained differential speed of the field, leading to a vacuum refraction index which depends on the mass, with seizable effect for large mass (i.e. for Compton wavelengths comparable with the "topon", the "space distance" between neighbor gates). QCFT solves a number of logical and mathematical problems that plague QFT, allows a unified framework for different fields, giving a mechanism for relativistic invariance, and providing the natural framework for a theory of Quantum Gravity. If there is time, at the beginning of the talk I will also mention the list of purely operational postulates for QT that we recently derived with Chiribella and Perinotti, and which are all of informational nature. Thus we can now really say that "Physics is Information" as Wheeler said, not "Information is physical" as Landaurer said.